[cgriswald]

It still seems pretty outlandish at an interstellar scale. Life would have to survive ejection, survive space, actually hit a target, survive injection, and be compatible with the new environment.

All that and life still has to evolve somewhere in the first place.

[nix23]

>survive ejection, survive space, actually hit a target, survive injection,

Billions of Bacteria's have billions of chances.

>and be compatible with the new environment

Water from 0-98C

[cgriswald]

Billions of chances might not even get you out of the star system. And even with 100 million years of time you might not find another star system. If you do, you need to go into orbit or you’re nearly guaranteed to not hit anything. And you’re most likely to hit either the host star or a gas giant. If you do manage to hit a rocky body with water and survive, you still have to land in a place that gives you access to that water. The odds are literally astronomical.

Of course water by itself isn’t enough. You’ll also need the correct chemical makeup, pressure, light, temperature range, etc. And you’ll need enough energy and materials to reproduce enough that random mutations can bootstrap an ecosystem before your monoculture consumes all the food and starves itself to death.

[nix23]

>Of course water by itself isn’t enough. You’ll also need the correct chemical makeup, pressure, light, temperature range, etc.

Something like Underwater Volcanoes to Arctic sea, from Sulfuric Acid-water to something like Lake Natron?

>Billions of chances might not even get you out of the star system.

"might" is the perfect expression ;)

[cgriswald]

Hot spring bacteria won’t survive the arctic and vice versa. Whichever specific bacteria make the trip have to find themselves in an environment specifically non-hostile to that bacteria.

Might is a fine word, but eventually the odds are so unlikely you have to conclude its impossible or at least that independent abiogenesis is more likely. It’s also possible to take a step back and consider molecular panspermia or other theories.

[nix23]

>Hot spring bacteria won’t survive the arctic and vice versa.

No but can adapt, any discussion about it is just plain stupid, the chance is small but give the mass of chances over time it's not that small anymore, you know like intelligent life on another planets.

[cgriswald]

> No but can adapt,

It can't adapt if it is killed off by the initial conditions.

> the chance is small but give the mass of chances over time it's not that small anymore

The likelihood of a lifeform surviving such a trip and seeding a new planet even once is, in my opinion, incredibly small.

But panspermia doesn't mean, "this happened one extremely lucky time because there were so many attempts over the eons the universe has been around." It means that this is the means by which life regularly spreads across the cosmos.

It's important to note that each of these numbers is teeny tiny and small. You need lots and lots and lots and a lot more lots of separate chances to reach something approaching certainty. Your units probably need to be life-bearing rocks/ice, not individual bacteria. Although more bacteria means it is likelier to survive the trip and thrive in the presence of enough resources, most of the filters on this trip (say smashing into a star) take out the whole rock, not just a few unlucky bacteria on that rock.

I'm much less skeptical of life spreading this way within a star system and of the molecules of life being formed in the cosmos and then seeding planets (i.e., molecular panspermia).